Oldsmobile 400 425 455 MID-AIR™ MidRise Aluminum Intake Manifold [Black] Speedmaster has chosen the most

Speedmaster has chosen the most popular diameters for their pulleys

These aluminum housings simply replace the stock cast iron housing

carb gaskets

They come in many sizes to meet just about all of your needs

Oldsmobile 400 425 455 MID-AIR™ MidRise Aluminum Intake Manifold [Black] Speedmaster has chosen the mostThe Speedmaster MID AIR design features the identical plenum and runner design as the normal mid rise. The main difference is that there is an open area under the plenum chamber. This feature is sometimes called an air gap design. The air flowing under the plenum provides a cooler charge for the incoming air with less heat transfer from the engine. This cooler air charge provides additional power and torque.